1. Field of Invention
This invention relates generally to devices for squeezing and expelling the contents of collapsible tubes, and specifically to such devices having rollers and being small and economical in construction.
2. Description of Prior Art
Thin-walled collapsible tubes have long been popular as containers for items such as toothpaste, cream, and other paste-like materials. A great number of devices have been invented to squeeze and expel the contents of such tubes. Many of these suffer, however, from being excessively complex and uneconomical to produce.
Some simple devices work by winding the tube with a key, but these do not function well with plastic tubes which are resilient and tend to unwind. Furthermore, most devices of this type have the added inconvenience of requiring the tube to be subsequently unwound in order to disengage the key from the tube.
Other devices expel the tube contents without requiring the tube to be wound. The simplest of these is a block with a through-going slit into which the tube is inserted. The user pushes the block toward the nozzle end to flatten the tube and expel the contents. A major disadvantage of this type of device, however, is that the slit width is fixed and therefore not appropriate for all tube wall thicknesses.
Still other devices utilize one or more rollers to perform the squeezing action. The primary advantage of squeezing by a rolling rather than sliding action is that inherently less force is required to advance the device forward. U.S. Pat. No. 3,586,213 to John B. Gill (22 Jun. 1971) presents a device with two toothed rollers and two U-shaped handles. As the handles are manually squeezed together the rollers are brought to bear on the tube, and as one of the rollers is turned with a crank the tube is squeezed and crimped, and the device advances forward. The amount of squeezing pressure that can be applied to the tube is limited only by the strength of the user and ultimately by the strength of the device itself, and as such very stiff tubes such as those made purely of metal and containing very viscous contents can be effectively squeezed. However, the device does not function well with plastic tubes which due to their resiliency are not amenable to crimping, and thus back-flow of the tube contents can occur if the handles are released. Additionally, the teeth of the rollers can cause tears in plastic tubes if excessive force is applied. A further disadvantage of the device of Gill, true for all types of tubes squeezed, is that the user must continuously squeeze the handles together as the device advances forward, a fact which may cause difficulty or be an inconvenience for some individuals.
U.S. Pat. No. 1,773,104 to Stanley G. Johnson (19 Aug. 1930) presents a device which also employs two rollers to squeeze the tube, but the squeezing action is carried out by springs rather than by manual pressure. Although the user is alleviated of the task of squeezing, no easy means of advancing the device forward is provided. The user is expected to hold the tube with one hand, and with thumb and forefinger turn the two knurled rollers. A further disadvantage of this device is that no means of opening the rollers to allow the tube to be inserted is provided. Moreover, once the contents of the tube have been expelled, the lack of means of opening the rollers requires that, as with the devices employing keys, the device must be operated in reverse in order to be disengaged from the tube.
U.S. Pat. No. 4,405,062 to Eraine J. Tschida, Sr. (20 Sep. 1983) presents a device with two opening levers, two elastic bands, and two roller-shaped jaws. When the levers are squeezed, the jaws open, thereby permitting insertion or extraction of the tube. When not being squeezed, the levers, with the aid of the elastic bands, clamp down against the tube, thereby preventing back-flow of tube contents. Despite these advantages, this device still suffers from requiring the user to manually compress the jaws together in order to squeeze the tube and push the contents forward. Additionally, because the levers and the jaws look similar, there is the possibility of confusing the orientation of the device.
U.S. Pat. No. 3,414,166 to Paul G. Martin (3 Dec. 1968) and UK patent application GB 2,052,434 A to Rodney W. Park (28 Jan. 1981) both present wall-mounted devices which employ rollers and springs to squeeze the collapsible tube. Both of these devices suffer, though, from being overly large and consisting of many parts, and are therefore not of economical construction. Additionally, neither device provides a means of separating the rollers, which would permit rapid tube insertion and extraction. Finally, the device of Park suffers additionally from requiring a ratchet mechanism or a gravity-assisted arrangement to advance forward along the collapsible tube, both of which add greater complexity.